Deploy BFD and OSPF association on the direct link. If the physical link is disconnected, please arrange the BFD processing process in order.

Question

Options

• AThe correct sequence is: 1. BFD quickly detects link failures; 2. The BFD session status changes to Down and notifies the corresponding device; 3. The corresponding device notifies the local OSPF process that the neighbor is unreachable; 4. OSPF recalculates routes.
• B
• C
• D

• A
  70% (33)
• B
  9% (4)
• C
  17% (8)
• D
  4% (2)

Explanation

Option A correctly describes the BFD-OSPF failure detection chain in the proper order: BFD acts as the fast-detection layer, so it is always the first to sense the physical link failure, typically within milliseconds, long before OSPF's own hello/dead timers would expire. Once BFD detects the failure, it transitions its session to the Down state and sends a notification to the peer device, which is the correct trigger mechanism before any routing protocol action occurs. Only after receiving that BFD notification does the device inform its local OSPF process that the neighbor is unreachable, prompting OSPF to run the SPF algorithm and recalculate routes. Options B, C, and D are not provided with content, so they represent incorrect or incomplete alternatives by default.

Memory tip: Think of BFD as a watchdog that alerts OSPF, not the other way around. The order flows strictly downward - hardware link fails, BFD reacts, BFD tells OSPF, OSPF rerouts. Any sequence that skips BFD's Down notification or has OSPF acting before being informed by BFD is wrong.

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